The Slow Cook has a post on a guy in Portland, Oregon, who got tired of waiting for a plot at a community garden, so he used Google maps to locate nearby empty city lots. Then he contacted owners about gardening on the vacant properties. One woman replied:
The landowner had recently received a nuisance complaint from the cityabout the buildup of refuse on the lot. She was elated that I would
clean up the lot and turn it into a garden. In exchange for the use of
the land, I am providing her with approximately one CSA
share of produce for 16 weeks. We drew up an agreement, and she
promises to give me as much advance notice as possible should she
decide to sell. She also offered me a lot four times the size of this
one, about 20 blocks away, which I hope to use next year.
The risk, of course, is that in a few years he'll lose the land and all the work he put into it, but then I imagine there will be other plots for the taking.
Let every empty city lot be a garden! Imagine.
More on the garden here.